The staff may be the oldest multi-purpose tool known to man. In addition to serving as an aid in mobility, the staff has also been modified to serve many other purposes. Until modern times, staffs that were designed for support have also served as the primary probing tool for use by the blind.
Today, the "long cane" is the most common probing tool in use by the blind. These canes are not used for weight bearing or support. The long cane, and the sophisticated foot travel technique associated with it, dates back to organized rehabilitative efforts developed for returning veterans blinded in WWII. It was found that by lengthening and lightening the traditional crook-handle support cane or staff, sweeping probing techniques could be used. Blind persons could extend the "long cane" outward as a tool, while moving it in sweeping arcs form side-to-side for exploring terrain.
The gripping areas of long canes are generally based on some variant of a circular grip or a golfer's putter grip adapted for use on a straight-axis circular shaft. Specifications of the long cane with a crook-handle may be found in Foundations in Orientation and Mobility, American Foundation for the Blind, 1987. When the traditional crook-handle support cane was lengthened, the straight circular shaft adjacent to the crook was able to serve as the gripping area. In usage, the crook of the handle was oriented downwards and served as a counter-balance for the shaft. The crook-handle has disappeared on many models of long canes, and commonly the straight-axis putter and circular grips serve without the counter-balance of the crook.
There are functional problems heretofore with circular, specialized, and adapted designs of long cane grips. The grips lack a practicable shape and distribution of mass that allows an effective method of counter-balancing for comfort and control. The grips lack an effective shape for optimum overall usage, and more specifically, they lack a versatility for use in both extended and upright positions.
The shape of the grips, with the exception of a custom-designed malleable plastic grip molded for a specific person's hand, causes a maladaptive deviation of the wrist that promotes a chain reaction of harmful effects including improper postural alignment and fatigue. The basic problem with the circular and straight-axis grips found on long canes is that when firmly grasped and manipulated they force the wrist into an abnormal position, a deviation from a straighter alignment that is preferable for manipulation of a tool.
Specialized grips for long canes are those grips which have been customized by actually molding the grip to the shape of the hand. A disadvantage of this technique is that the grip lacks versatility. Because the fight and left hands have a different dexterity, and because they may not be exactly identical in shape, a molded personal grip is limited to one hand. In addition, the use of finger grooves on molded grips can cause problems for persons whose hands do not fit the grooves.
Adapted grips are grips which have been adapted from other uses to be used on long canes. Each adapted grip has unique problems. For example, curved ax handles have been tried on long canes. Curved ax handles have a similar slant as the Versatile and Universal Handle, but they have a distinctly different cross-sectional configuration, and in particular they are narrower. Firmly grasping a curved ax handle causes the wrist to deviate from a straight position and the hand enters into a locked upraised grip. The constant usage pattern of the long cane creates the need for allowing a more neutral position of the wrist that accommodates a pattern of movements including a frequent tapping, lifting, and sweeping from side to side. Because of this, a common curved ax handle is not appropriate for these sweeping patterns of movement.
The golfer's putter grip is a very common adapted long cane grip. The putter grip has a flat area designed for placement of the thumbs on top of the grip. This putter grip has been adapted for use on the long cane by orienting the flat area to the side for placement of the index finger. This usage, however, increases the repetitive use of the index finger. An ergonomic design guideline is to minimize the repetitive use of the index finger for manipulation and rely more on the thumb if possible. The muscles that control the thumb are particularly well suited for manipulation of a tool. The index finger is not as well suited for tool manipulation, but is effective in interpreting vibration and also in gently controlling the stroke of the long cane. The excessive use of the index finger for gross manipulation not only causes fatigue, but this pattern diminishes the capability of the index finger to be used for interpreting vibrations and other more appropriate sensory functions. Details of preferred hand positions may be found in Human Factors in Engineering and Design by Sanders and McCormick.
Another problem with the putter grip is that the relatively small contact surface area of the grip, when it is adapted to long cane use, creates pressure points on the hand. An ergonomic design guideline is to provide a substantial contact surface area to distribute pressure on the hand more evenly, wherein handling of a tool or other implement is more comfortable and less stressful.
For a variety of implements, there have been many attempts to achieve a proper alignment of the wrist by changing the bend or angle of attachment of a commonly used grip. This has been tried on such devices as hammers, crutches, and ski poles. But it has been found that, in addition to the bend of a handle and its angle of attachment, the cross-sectional shape of the surface being gripped determines the position of the wrist when a handle is firmly grasped.
Accordingly, the principal objects of the claimed invention are to provide an improved handle with a shape that promotes correct posture and ergonomically correct patterns of movement; to provide a handle with a substantial contact surface area that conforms to a natural grip of the hand; to provide a handle that allows a firm yet relaxed grip that does not unnecessarily tense the muscles and restrict the range of movement; to provide a handle that accommodates use by both hands yet also accommodates the special dexterity of each hand; to provide a handle that allows a natural alignment of the hand which does not force the skeletal structure to lose its optimum efficiency as a support; to provide a handle that allows the muscles to move the body more easily; to provide a handles that does not hasten fatigue; to provide a handles that does not require excessive manipulation of the index finger, yet allows the index finger to be properly used for tactile interpretation and control. It is yet a further objective to provide a handle with a practicable shape and distribution of mass that allows an effective method of counter-balancing. Also it is an objective of the invention to provide a handle with a versatile and universal design that may be used in different orientations for special or combined purposes, including use as a probing and support device that helps a person move about and explore the environment.